The invention relates to a sewing machine electronically storing the stitch control data which are sequentially read out to produce various patterns of stitches. More particularly the objective of the invention is to control the basic or reference needle position of a member of patterns which are produced sequentially in combination by such a type of sewing machine.
In a zigzag sewing machine which may produce various patterns, it is generally required to produce the stitch patterns with a predetermined basic (or reference) needle position which may be located at the right end, left end or the middle of the maximum swinging range of the needle most properly for the patterns. In case the sewing machine operator wishes to produce a number of patterns sequentially in combination especially with adjustment of the needle swinging amplitude, it is undesirable that the needle swinging amplitude be adjusted on both sides of the basic needle positions which may be different in dependence upon the different patterns. Namely, it is undesirable to shift the basic needle positions each in dependence upon the different patterns. It is therefore a primary object of the invention to memorize a combination of different patterns with designation of a basic (or reference) needle position common to these patterns.
According to the conventional sewing machine producing stitch patterns including straight stitches, the straight stitches are produced with a basic needle position generally set at the center (or middle) M of the maximum swinging range of the needle. It is actually desirable for many stitch patterns including zigzag stitches to set the basic needle position at the center M of the maximum needle swinging range. This requirement, however, different with respect to a pattern such as a pattern of a tulip as shown in FIGS. 1(A) and 1(B). As to the patterns such as the tulip, it is preferable to set the basic needle position at the left end L of the maximum needle swinging range, because such a pattern is easily positioned with the basic needle position L with respect to the fabric to be sewn, and because the pattern may be varied in size from minimum to maximum with reference to the basic needle position L. As to the pattern of blind stitches, it is preferable to set the basic needle position at the left end L of the maximum needle swinging range, because such stitches are produced with reference to the edge of the fabric to be sewn. No problem arises if the different stitch patterns of different basic needle positions are produced separately and individually. A problem arises if these patterns are produced sequentially in combination. Namely, the difference of basic needle positions prevents the combination of patterns from being produced in alignment with each other. Actually if the combined patterns of different basic needle positions are produced in the maximum size in the maximun needle swinging range, these patterns are produced in alignment with each other and no problem arises as shown in FIG. 1(A). On the other hand, if the size of these combined patterns are adjusted (or reduced), these patterns are so reduced with reference to the difference basic needle positions each specific to the patterns, and as the result, the sequential patterns are produced to and fro out of alignment.